Dove Cliff Weir Removal: River Restoration or Heritage Vandalism?
Christopher Grzesiok / Paul Herickx Fisheries Technical Specialist / Project Manager 25/09/2019 Project Objectives
1. Reducing the risk associated with the Environment Agency’s assets* at this location 2. Restoring the River Dove beyond Dove Cliff Weir
* includes 2 weirs, a sluice gate and mill leat channel
2 ~5km
3 This is Dove Cliff Weir…
70m
2m
4 Why?
• It’s in the UK’s 25 year Environment Plan • Salmon 5 Point Approach
• Health and Safety Risk • Redundant asset • Ongoing financial costs
• On its own Dove Cliff currently completely blocks or delays ecological migration of up to 1187km, which equates to 90% of the catchment What about all of the other barriers? • there are currently 460 known barriers • equates to 1 barrier every 2.87km • 5 have formal fish passes • 6 have been removed or fallen down • 3 have easements • 3 are currently in design or build for 2019/20 • 5 more are currently being developed within the catchment partnership • = 22 / 460 (4.8%) 7 …and so what? • Focussing on priority structures means that we are working towards opening up 46% of the catchment to free fish movement or 42% (550km) of river length by the end of 2020 • However, all of this success is reliant on one structure which we own…
8 Timeline
2009/10 - Feasibility Study 2010/11 - No funding 2011/12 - Design (Fish Pass) 2012/13 - Feasibility (Weir Removal) Heritage 2014/15 - No funding 2015/16 - Design of removal 2016/17 - Structural Survey of weir 2017/18 - Design of removal continued 2018/19 - Design completed 2019/20 - Weir removal starts 1st of September
9 Dove Cliff Heritage Not formally mentioned in the Domesday book (1086), however, work for the channel would have started between 1086 and 1342 • Cliff Mill first mentioned in 1342 • Operated as a corn mill until 1733 • 1753 – 1881 it was used to power a forge • Mill demolished in 1963
10 11 Design Development – challenges
• Heritage • Severn Trent Water – abstraction plant • Severn Trent Water – sewer • Clay Mills Leat • Monks Bridge Aqueduct • Geomorphology
12 Detailed Design – Aerial View
13 Detailed Design – Main Weir
Sloping Low Flow Channel
14 Detailed Design - Heritage
• New riverbank profile • 10-15m section retained • Root protection geotextile • Re-use of existing and demolition materials
15 Detailed Design – Severn Trent Water
Flow Split Sewer
16 Detailed Design – Low Flow Management • Existing clay centre retained
• 0.5m x 0.5m ‘blockstone crest’
• Changing gradients throughout design
17 Construction – Temporary Works River Diversion
http://193.192.196.65:2010/Streaming/Channels/1/picture18 River Restored for Christmas 2019? There is no innovation without experiment, no experiment without failure and no achievement without risk. Therefore the biggest risk is not taking any risk.
19 Questions?
20